1. Field of the Invention
The present disclosure generally relates to image processing and, more particularly, to a generation process and a reverse process of a Bayer image in an image processing apparatus.
2. Description of the Related Art
In recent years, images corresponding to full high definition (HD) with an image size of 1920 (horizontal (H))×1080 (vertical (V)) are used in television broadcast and the like. Further, recently, to generate a video work with a definition higher than that of the full HD image, in particular in the movie industry and the like, an image capturing apparatus is desired which can record an image with a definition higher than that of the full HD image, such as an Over HD image (for example, 4K horizontal×2K vertical: K=1000).
Therefore, to realize the image capturing apparatus described above, a complementary metal-oxide-semiconductor (CMOS) sensor having pixels, the number of which corresponds to 4K horizontal×2K vertical, is used in the image capturing apparatus. As the CMOS sensor, one having a Bayer structure, in which color filters of four colors (R/Gr/Gb/B) are arranged in a checkered pattern, may be used (the four colors (R/Gr/Gb/B) refer to colors including red (R), green next to the R in one direction of a pixel array (Gr), blue (B), and green next to the B in the one direction (Gb)). Therefore, an output signal from the CMOS sensor is a video signal of the Bayer structure, so that a white balance correction, a defect correction, and a correction of decrease in marginal illumination are performed on the video signal, and thereafter, a video signal of one frame (for example, 1/60 second) is recorded in a memory such as synchronous dynamic random access memory (SDRAM) or the like. The recorded video is further recorded in an external recording device through a 3 Gbps Serial Digital Interface (3G-SDI) transmission path by using a transmission standard compliant with Society of Motion Picture and Television Engineers (SMPTE). The following flow is applied to images recorded in the external recording device by using a personal computer (PC): an interpolation process is performed on a Bayer image of 4K×2K to generate a RGrGbB image with a size of 4K×2K and video signal processing such as color processing and edge enhancement is performed on the RGrGbB image to generate a final video signal of 4K×2K.
When generating a three dimensional (3D) image, a mirror for making a mirror image of an image of one of two image capturing apparatuses and the two image capturing apparatuses are used, so that an image output from one image capturing apparatus and an image output from the other image capturing apparatus are matched to each other vertically or horizontally. Therefore, the image capturing apparatus is required to have a scan reverse function to reverse an image. Japanese Patent Application Laid-Open No. 2000-261793 discloses a configuration to realize the scan reverse that is a function to reverse an image. When image data is read from a frame memory which temporarily stores an output image from an image capturing element, a memory that indicates a sequence of reading image data is controlled, so that an image in the frame memory is freely reversed vertically, horizontally, or vertically and horizontally. Thereby, an image reversal can be changed freely by the control for reading image data from the frame memory. However, in the Bayer image which is an output image from the image capturing element, color filters (R/Gr/Gb/B) are arranged in a checkered pattern, so that there is a problem in that a color signal of a first pixel of the Bayer image before reversing the image is different from a color signal of a first pixel of the Bayer image after reversing the image. In this case, when performing various signal processing operations (false color processing, edge enhancement, and band limitation for each color) on the Bayer image output from the image capturing apparatus by using external editing application software, a first pixel of the image is changed to another color signal. Therefore, if signal processing is performed assuming that a color of the color signal of the first pixel of the recorded Bayer image corresponds to a color of the color signal of the first pixel of the Bayer image output from the CMOS sensor, there is a problem in that an LPF that limits the band of each color and the false color processing do not function properly, and the image quality may degrade.